论文总字数：52898字

摘 要

本设计是根据设计任务书的要求和《公路桥规》的规定，优化设计上海市松浦三桥主桥方案。首先根据工程概况和规范要求进行该桥的方案设计和比选，选定的方案为变跨度四跨预应力混凝土连续梁桥，采用单箱双室变高度箱型截面，腹板形式为斜腹板， 施工方式为悬臂浇筑施工。根据公路桥规和设计手册初步拟定桥跨布置和截面尺寸后，利用 Midas 软件建立桥梁模型并计算结构的恒载、活载及次内力等荷载，接着进行荷载组合并画出包络图；然后手算预应力钢筋的估算与布置、截面几何特性、预应力损失等；然后通过手算对上部结构进行验算，结果均满足设计要求。最后进行下部结构初步设计，采用盆式橡胶支座、双柱墩和桩基础。此外，本设计也进行了工程量预算、施工图绘制等工作。

关键词：方案设计 连续梁桥 预应力 悬臂施工

Design of Prestressed Concrete Continuous Girder Bridge for Main Bridge of No.1 Bridge of Shaohai North Road in Jiaozhou City

Abstract

According to the requirements of the design document and the regulations of Highway Bridge Regulation, this design compares and designs the main bridge of Three bridge matsuura in shanghai City. Firstly, according to the general situation of the project and the requirements of the code, the scheme of the bridge is designed and compared. The selected scheme is a variable-span four-span prestressed concrete continuous girder bridge, with single box and double chamber, variable height box section, and inclined web plate. The construction method is cantilever pouring construction. After drawing up the layout and section size of the bridge span according to the highway bridge gauge and design manual, the bridge model is established by using Midas software, and the dead load, live load and secondary internal force of the structure are calculated, and then the load combination is carried out and the envelope diagram is drawn. Then calculate the calculation and arrangement of the prestressed steel bar, the geometric characteristic of section, and the loss of prestressing force. Then the superstructure is checked by hand calculate, and the results meet the design requirements. Finally, the preliminary design of the substructure is carried out, using the basin rubber bearing, the double column pier and the pile foundation.In addition, this design also carries on the project quantity budget, the construction drawing and so on work.

Key Words: Design; Continuous girder bridge; Prestress; Cantilever construction

第一章 方案设计

跨径布置

• • 1. 标准跨径

松浦三桥主桥起点桩号：K5＋450，实际桥长 440m，本联设计采用变截面连续箱梁结构形式。为了在整体上确保桥的美观及整体性，布置跨径时，前后联保持协调，通过调整，最终确定本联的跨径布置如下：

80m 2×140m 80m=440m

图1-1 标准跨径布置图（单位：m)

由图1-1可知本联为四跨连续梁桥，且为跨河桥，适宜对称悬臂施工。根据参考文献，对称悬臂施工变截面连续梁桥边中跨比一般为 0.5~0.65。故该桥中所选择的边跨与中跨的比为 0.57:1。

• • 1. 计算跨径

以上的跨径布置称为标准跨径，而计算跨径需要考虑到两个边跨支座尺寸及伸缩缝的折减。为了降低伸缩缝的长度，所以把固定支座放在 3号墩上，这样可以使梁向两边伸缩。由于本桥的混凝土材料的温度膨胀系数为 1.0×10-5/℃，设计年平均温差为±20℃，所以左右两边分别预留3cm的伸缩缝宽度；综合上述规定，计算跨径布置如下图 1-2：

0.5m 79.5m 2×140m 79.5m 0.5m

图 1-2 计算跨径布置图(单位：m）

79.5m 2×140m 79.5m

顺桥向设计

• • 1. 纵坡设计

考虑到桥梁纵向排水，本设计桥梁纵坡坡度取为 1.5%。纵坡坡度相对而言可忽略不计，对跨径和梁高的影响很小，故在后面的MIDAS建模和计算中，按平坡设计。

• • 1. 梁高设计

2号墩、3号墩、4号墩支座处梁高：根据参考文献[1](P228)，一般取最大跨径 L 的 1/15~1/20，本设计取7.5m。

中跨跨中梁高：根据参考文献[1](P229)，一般按构造要求为 1.5m~4.5m，也可按

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